package com.lcxw.hxzbcommon.common;

import java.nio.charset.StandardCharsets;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class AesCBCUtil {

    /*
     * 加密用的Key 可以用26个字母和数字组成
     * 此处使用AES-128-CBC加密模式，key需要为16位。
     */
    private final static String sKey = "lcxw_ywpd_202001";
    private final static String ivParameter = "lcxw_ywpd_202001";
    private static AesCBCUtil instance = null;

    private AesCBCUtil() {
    }

    public static AesCBCUtil getInstance() {
        if (instance == null) {
            instance = new AesCBCUtil();
        }
        return instance;
    }

    /**
     * 加密
     *
     * @param sSrc src
     * @return encrypted
     * @throws Exception ex
     */
    public String encrypt(String sSrc) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        byte[] raw = sKey.getBytes();
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        IvParameterSpec iv = new IvParameterSpec(
            ivParameter.getBytes());//使用CBC模式，需要一个向量iv，可增加加密算法的强度
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
        byte[] encrypted = cipher.doFinal(sSrc.getBytes(StandardCharsets.UTF_8));
        return new BASE64Encoder().encode(encrypted);//此处使用BASE64做转码。
    }

    /**
     * 解密
     *
     * @param sSrc src
     * @return original
     * @throws Exception ex
     */
    public String decrypt(String sSrc) throws Exception {
        try {
            byte[] raw = sKey.getBytes(StandardCharsets.US_ASCII);
            SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            IvParameterSpec iv = new IvParameterSpec(ivParameter.getBytes());
            cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
            byte[] encrypted1 = new BASE64Decoder().decodeBuffer(sSrc);//先用base64解密
            byte[] original = cipher.doFinal(encrypted1);
            return new String(original, StandardCharsets.UTF_8);
        } catch (Exception ex) {
            return null;
        }
    }

    public static void main(String[] args) throws Exception {
        // 需要加密的字串
        String cSrc = "我来自中国";
        System.out.println(cSrc);
        // 加密
        long lStart = System.currentTimeMillis();
        String enString = AesCBCUtil.getInstance().encrypt(cSrc);
        System.out.println("加密后的字串是：" + enString);

        long lUseTime = System.currentTimeMillis() - lStart;
        System.out.println("加密耗时：" + lUseTime + "毫秒");
        // 解密
        lStart = System.currentTimeMillis();
        String DeString = AesCBCUtil.getInstance().decrypt(enString);
        System.out.println("解密后的字串是：" + DeString);
        lUseTime = System.currentTimeMillis() - lStart;
        System.out.println("解密耗时：" + lUseTime + "毫秒");
    }
}